Saturday, 21 November 2009

Basis on qNMR: Rudiments

When I started playing drums, so many years ago, I kept hearing about so-called "Drum Rudiments". By that time, I was too young to realize how important they were and to me, they appear just as boring and repetitive exercises. However, rudiments (basic building blocks or "vocabulary" of drumming) are absolutely essential to master drums (something I have to admit I never achieved :-) )

In the last few years I’ve had the opportunity to meet and interact with many chemists who are using our NMR software. Some of them are NMR specialists with an outstanding knowledge from whom I have learnt a lot. On the other hand, other chemists use NMR on daily basis simply to confirm the structure(s) they have just synthesized but do not have a deep grasp of the inner details of NMR theory and signal data processing. Whilst I understand that in general this is fine, I have noticed recently that many of these less-experienced NMR scientists are now getting involved in more advanced NMR studies and, in my humble opinion, the lack of some important rudiments can lead to an improper interpretation of the NMR data.

One interesting example is quantitative NMR (qNMR), a field which is being used increasingly in the pharmaceutical industry, for instance, to quantify impurity levels, but it’s also very important in the field of natural products (see for example J. Nat. Prod. 2007, 70, 589-595) and for the calibration of other quantitative techniques such as HPLC. Typically, qNMR is based on obtaining quantitative information through integral-based calculations so in principle, it might seem as this is something trivial which does not require any additional effort. Whilst this is generally true, there are some very important rudiments which I think are worth pointing out.
The rudiments I will present in this series of articles will range from basic concepts on NMR Integration to more advanced deconvolution techniques, including our newly developed Global Spectral Deconvolution algorithm, GSD.
So if you have any interest in qNMR, watch this space. I promise to post these qNMR rudiments on a regular basis.


stan said...

NMR was always used as a quantitative technique, I think. Why should the quantitative aspect suddenly become kind of underlined and even merit a special acronym (qNMR). Isn't it, as the Italians would put it, somewhat like re-discovering "hot water" ?
Ciao, Stan

Santi Dominguez said...

I would say it is more like rediscovering platform shoes. You can do that several times, normally at 15/20 year intervals.

I think the point is that, with the advent of open access NMR labs, it is becoming possible for more chemists to get involved in this kind of quantitative (intermolecular mainly,intra molecular has never been sent to the back of the wardrobe) study. Hence the renewed interest, which we are definitely seeing.

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